Continue below to view the complete set of loglines for each episode of The Avengers: Earth's Mightiest Heroes.
The guide is presented via production order, details provided by Marvel Animation, though each episode features airdate information.

Please note the first five episodes of the series are each comprised of four "micro-episodes," five-minute installments which add up to a full 20-minute episode.

Episode #1: Iron Man is Born001a - Iron Man is Born!Original Airdate: September 22nd, 2010
When the villainous organization known as HYDRA attacks the United Nations, the fate of the world's leaders rests in the hands of Tony Stark, the Invincible Iron Man!001b - Hydra Lives!Original Airdate: September 25th, 2010
Iron Man may have finally met his match as the villainous organization known as HYDRA unleashes the Dreadnoughts against him, mechanized war machines built from technology that Tony Stark himself created!001c - Behold, the Mandroids!Original Airdate: September 27th, 2010
With backup from the world peacekeeping task force known as S.H.I.E.L.D., Iron Man faces down HYDRA. But are his allies any better than his enemies? Who can Tony Stark really trust?001d - Nick Fury, Agent of SHIELDOriginal Airdate: September 30th, 2010
S.H.I.E.L.D. Director Nick Fury must fight alone when the Grim Reaper infiltrates the high tech super villain prison known as the Vault!

Episode #2: Thor the Mighty!002a - Thor the Mighty!Original Airdate: September 26th, 2010
The villainous Wrecking Crew is tearing through New York City. The only thing standing in their way? The Mighty Thor!002b - The Seige of AsgardOriginal Airdate: September 29th, 2010
Thor is summoned back to his home of Asgard to find the realm eternal under siege by an army of Frost Giants. Now only the might of Thor's legendary hammer Mjolnir can turn the tide!002c - My Brother, My EnemyOriginal Airdate: October 2nd, 2010
The assault on Asgard was thwarted, but the mastermind behind the attack has yet to join the fray. Enter Loki, Thor’s most cunning foe…and his brother.002d - The Isle of SilenceOriginal Airdate: October 3rd, 2010
Banished to the Isle of Silence, Loki contemplates the events that lead him here. Did he truly lose the battle for Asgard, or have his sinister machinations only just begun?

Episode #3: Hulk Versus the World003a - The Coming of the HulkOriginal Airdate: September 23rd, 2010
Forever a man on the run, Bruce Banner heads to Las Vegas to track down an escapee from the super villain prison known as the Cube. But he gets more than he bargained for when a confrontation with the Absorbing Man causes him to transform into the Incredible Hulk.003b - Hulk Versus The WorldOriginal Airdate: September 28th, 2010
The battle rages as the Incredible Hulk trades blows with the Absorbing Man across the Nevada desert. Just when it seems like things can't get any worse the Hulkbusters join the fray with orders to take down the Hulk!003c - This Monster, This HeroOriginal Airdate: October 1st, 2010
The Hulk may be able to take on tanks, assault choppers, and heavy artillery, but what about two of S.H.I.E.L.D.’s most highly trained agents? Introducing…Hawkeye and the Black Widow!003d - Beware the Widow's BiteOriginal Airdate: October 10th, 2010
Clint Barton--codename Hawkeye--has faced his fair share of super villains in the past, but something doesn't sit right about his last encounter with the Incredible Hulk. Why did the Hulk save his team? And what's going on behind the scenes that Clint doesn't know about?

Episode #4: Meet Captain America004a - Meet Captain AmericaOriginal Airdate: October 5th, 2010
News from the front! Witness the story of Steve Rogers, the man who would become Captain America!004b - The Red Skull StrikesOriginal Airdate: October 6th, 2010
In the heat of World War II, Captain America and Bucky mount a desperate assault against a top-secret HYDRA base in Norway. But things take a turn for the worst when they come face to face with HYDRA's own Super Soldier...the nefarious Red Skull.004c - If This Be DoomsdayOriginal Airdate: October 7th, 2010
HYDRA's maniacal scheme to win World War II rages out of their control--and in the midst of the chaos, a chance for Captain America and Bucky to stop the Red Skull, once and for all!004d - Lo, There Shall Come a ConquerorOriginal Airdate: October 9th, 2010
His name is Kang the Conqueror. He is the undisputed ruler of Earth in the 40th Century AD, and he has a problem. There is a disturbance in the time stream--his entire reality is being wiped from existence, and the entire disturbance has a single source: Captain America.

Episode #5: The Man in the Ant Hill005a - The Man in the Ant HillOriginal Airdate: September 24th, 2010
When microbiologist Hank Pym obtains a rare sample of a metal called Vibranium to study, the villainous Klaw comes to steal it...but Klaw isn't prepared to enter Hank's world: The world of Ant-Man!005b - Enter the Whirldwind!Original Airdate: October 4th, 2010
When Super-Villain-for-Hire Whirlwind robs a lab at Greyburn College, it’s up to the wondrous Wasp to put an end to his crimespree days for good!005c - The Big HouseOriginal Airdate: October 11th, 2010
The astonishing duo of Ant-Man and Wasp take you on a tour of the Big House, the world's smallest super villain prison.005d - Welcome to WakandaOriginal Airdate: October 8th, 2010
Welcome to Wakanda, the most powerful nation on Earth...you're just in time to see the fall of its king, the Black Panther.

Episode #6 - Breakout, Part OneOriginal Airdate - October 20th, 2010
Iron Man, Hulk, Thor, Ant-Man and Wasp have defeated some of the most powerful, dangerous Super-Villains on the planet. And once defeated, those criminals are housed in the super-villain prisons. But now, on a day like none other, those prisons open wide, simultaneously releasing ever single villain in a breakout like the world has never seen. Our heroes’ only hope is to band together… to become the Avengers.

Episode #7 - Breakout, Part TwoOriginal Airdate - October 20th, 2010
The Super-Villain breakout has begun, and it’s everything our heroes can do to stay alive! But when a mysterious fourth prison is revealed housing a being whose power dwarfs anything ever seen, the Avengers must join together for the first time. Because the man called Gravitron is now free. He’s after Nick Fury… but he’ll destroy the world to get to him.

Episode #8 - Some Assembly RequiredOriginal Airdate - October 27th, 2010
Iron Man, Thor, Hulk and more of Marvel’s greatest characters begin their lives as Avengers. But with a wild card like the Hulk on the team, and a little prodding from the villainous Enchantress, will the team be smashed by one of their own before they embark on their first mission?

Episode #9 - Living LegendOriginal Airdate - November 3rd, 2010
Frozen since WW2 and kept alive by the super soldier serum, Captain America is now a man out of time trying to discover his place in the world. But he may not have much of a chance, as his old foe Baron Zemo aims to destroy Captain America, even if that means going through the Avengers!

Episode #10 - Everything is WonderfulOriginal Airdate - November 10th, 2010
A business decision by Tony Stark leads rival Simon Williams to go to extreme measures for revenge… he seeks help from the Grim Reaper and AIM. Now transformed into the ionic powered Wonder Man, Simon takes the fight back to Tony Stark! But the only one there to defend Tony is the one Avenger who dislikes him the most… Ant-Man. Has Tony Stark changed? PLUS! Wasp and Thor versus MODOC!

Episode #11 - Panther's QuestOriginal Airdate - November 17th, 2010
The Prince of Wakanda has been stalking the Avengers for weeks, and now the Black Panther strikes! The Panther wants the Avengers help in taking back the throne of Wakanda from the vicious Man-Ape. The problem is, they have to go through the Wakandan army, HYDRA, and Klaw to do it.

Episode #12 - Gamma World, Part OneOriginal Airdate - November 26th, 2010
A dome of gamma energy envelops the Cube, turning everyone inside of it into a Gamma Monster. SHIELD and Doc Samson know that the Leader and a host of Super-Villains are inside… but worse, the dome is expanding. The Avengers are going in, but they’re not prepared for what they find inside. Meanwhile, Hawkeye catches up to the traitorous Black Widow.

Episode #13 - Gamma World, Part TwoOriginal Airdate - November 26th, 2010
The Leader’s master plan has been unleashed, and half of North America has been turned into Gamma Monsters, including the Avengers! In 24 hours, the entire world will be under the Leader’s control. Our only hope? Hawkeye. His only hope? Finding the Incredible Hulk and convincing him to stop the Leader from turning Earth into Gamma World.

Episode #14 - Masters of EvilOriginal Airdate - December 5th, 2010
Zemo! Enchantress! Executioner! Abomination! Wonder Man! Crimson Dynamo! Individually they are the most powerful Super-Villains on the planet. Together, they are unstoppable. Avengers Mansion is laid siege and one by one, the Avengers fall. And with the most powerful of them defeated, what hope do Black Panther and Hawkeye have?

Episode #15 - 459Original Airdate - December 12th, 2010
Something has fallen to Earth… something here to destroy us all. A Kree Sentry has arrived, heralding Earth’s entry into an interstellar war between two alien empires. And if Ant-Man and the Wasp don’t stop it, humanity is doomed. But they may have an ally living among them… Enter: Captain Marvel.

Episode #16 - The Man Who Stole TomorrowOriginal Airdate - January 9th, 2011
Kang the Conqueror has arrived in the 21st century with two goals… destroy Captain America and take over the world. The Avengers aren’t about to let either happen… until Kang explains why. Because in the near future, the Earth will be destroyed. Kang has come to save the world, and the Avengers are standing in his way.

Episode #17 - Come the ConquerorOriginal Airdate - January 16th, 2011
Kang’s invasion of Earth begins in earnest! A fleet of ships from the future unleash war on the planet, and the Avengers are helpless to stop it. But while Iron Man searches for Kang himself, Captain America takes charge of the Avengers… but to fight a war, you need an army. And Wasp knows where Cap can get one. Welcome to the other dimensional prison called 42, maintained by a robot called Ultron.

Episode #18 - The Kang DynastyOriginal Airdate - January 23rd, 2011
Kang the Conqueror’s takeover of Earth is well underway, and the Avengers launch a last ditch offensive to stop the time traveler’s plans. What hope do the Avengers have? Kang’s Damocles Base has the power to destroy the world, his technology is more advanced than anything Iron Man has ever seen, and his personal guards are unstoppable. But what secret is Kang hiding that could lead to his downfall?

Episode #19 - The Widow's StingOriginal Airdate - December 19th, 2010
Hawkeye’s still out to take down the Black Widow, and he’s going to shake down every Hydra agent on the planet to do it. Which is starting to tick off Nick Fury. Both Iron Man and Fury order Hawkeye to back off, but hey… it’s Hawkeye. So with SHIELD babysitter Mockingbird at his side, Hawkeye infiltrates Hydra Island to take the fight right to the Black Widow. Will Hawkeye finally trust somebody enough to save his life?

Episode #20 - The Casket of Ancient WintersOriginal Airdate - May 15th, 2011
On the hottest day of the year, an ancient artifact is found… and a cold wind
blows. An ancient Asgardian relic called the Casket of Ancient Winters has been
opened, and the entire planet goes into a deep freeze. But as the rest of the
Avengers deal with an invasion of Dark Elves and demons, Iron Man and Thor
must put aside their differences to battle Malekith the Accursed.

Episode #21 - Hail, Hydra!Original Airdate - May 22nd, 2011
Hydra and AIM are waging war against one another in the streets of New York,
and only one person knows why… the Black Widow. She knows that AIM has
created the ultimate weapon for Hydra, a weapon so powerful that MODOC
wants it for himself. It’s called the Cosmic Cube, and to touch it is to change the
world. But the Avengers have another problem… they’ve just been grounded by
SHIELD, now under the control of Maria Hill.

Episode #22 - Ultron-5Original Airdate - May 29th, 2011
Ant-Man has had enough of the violence and fighting and endless confrontations
with Super-Villains. He wants to find a better way to bring peace and order to the
world… after all, that’s why he created Ultron. But something has gone terribly
wrong. And now Ultron may well be the very last villain the Avengers face.
Because even an Avenger can fall.

Episode #23 - The Ultron ImperativeOriginal Airdate - June 5th, 2011
As the devastated team struggles with a loss, Ant-Man and Iron Man go about
destroying all remnants of Ultron. But they don’t realize that Ultron has
transcended his body, and has infiltrated the world’s computer systems.
Because the only way to bring peace to Earth is to eliminate those who would
cause chaos… and that’s all of humanity. Ultron has begun the end of the world.

Episode #24 - This Hostage EarthOriginal Airdate - June 12th, 2011
The end begins! As Thor and Iron Man work to find a way for Thor to return to
Asgard, the Enchantress makes her move. The Masters of Evil mobilize all
across the world preparing for an invasion the likes of which Earth has never
seen. Because unless the Avengers can stop it… the armies of Asgard are
coming to Earth.

Episode #25 - The Fall of AsgardOriginal Airdate - June 19th, 2011
Lost and separated, the Avengers struggle to survive in the nine realms of Asgard. But with Thor defeated and Iron Man’s armor not functioning… what chance do they have? As realm after realm falls, the Avengers join the resistance, heading for the final confrontation with Loki.

Episode #26 - A Day Unlike Any OtherOriginal Airdate - June 26th, 2011
Eight realms have fallen, and only Midgard remains. The Avengers are nothing against his power. Loki has won. Every moment has lead to this.